FIG. 12 shows a schematic configuration diagram of an existing general power supply system in a data center including a plurality of load apparatus, for example, a plurality of servers, having direct current voltage as a drive power supply. The power supply system includes an uninterruptible power supply system (UPS) 1 installed in a 400V system power supply, and an alternating current power distributor (PDU) 2 that converts high-voltage alternating current power (400V AC) supplied via the uninterruptible power supply system 1 into alternating current power of, for example, 200V or 100V.
Herein, the uninterruptible power supply system 1 basically includes a large capacity battery (BAT) 1a in which direct current power can be stored. Also, the uninterruptible power supply system 1 is configured to include an AC/DC converter 1b that converts the high-voltage alternating current power into direct current voltage, thus charging the battery 1a, and a DC/AC converter 1c that converts an output voltage of the AC/DC converter 1b or direct current power stored in the battery 1a into high-voltage alternating current power, and outputs the high-voltage alternating current power.
Herein, the power distributor 2 includes a breaker 2a that separates, for example, the system power supply and a load equipment side including the load apparatus (servers). Also, the alternating current power distributor 2 further includes a transformer 2b that converts the high-voltage alternating current power (400V AC) into alternating current power of, for example, 200V, and outputs the converted alternating current power. Reference sign 3 in the drawing is a transformer that converts transmitted alternating current power of, for example, 6.6 kV into the high-voltage alternating current power (400V AC), and draws the high-voltage alternating current power into a building in which the uninterruptible power supply system 1 and the like are provided.
Also, load equipment constructed to include a plurality of a server 4 as the load apparatus includes a switching power supply 5, connected to the power distributor 2 at the stage previous thereto, that generates low-voltage direct current voltage of 48V or less (for example, 12V DC), which is drive power supply voltage of the server 4, from the alternating current voltage (200V AC). The switching power supply 5 generally includes an AC/DC converter 5a that converts the alternating current voltage (200V AC) into direct current voltage, and a DC/DC converter 5b that converts the output voltage of the AC/DC converter 5a into direct current output voltage (12V DC) to be supplied to the server 4. Further, each of the plurality of the server 4 is connected to the switching power supply 5, and operates by the direct current output voltage, which is the drive power supply of the server 4, being supplied from the switching power supply 5 (for example, refer to PTL 1).
The plurality of the server 4 are generally installed housed in server racks to form server groups of a predetermined number each, and the switching power supply 5 is provided corresponding to each server group. Further, the switching power supply 5 is housed integrally with the predetermined number of the server 4 in the server rack. The plurality of the server 4 construct a so-called multinode server.
However, the existing general power supply system configured as heretofore described has a large number of conversion stages, such as the previously described AC/DC converters 1b and 5a and DC/DC converter 5b, and conversion efficiency with respect to power is poor. Therefore, power supply systems such that the kinds of direct current power supply system shown in FIG. 13 and FIG. 14 are constructed have been proposed.
The power supply system shown in FIG. 13 is such that high-voltage direct current voltage (400V DC) obtained from the AC/DC converter 1b of the uninterruptible power supply system 1 is supplied directly to a direct current power distributor 2. Further, the load apparatus side is configured so that the high-voltage direct current voltage supplied via the power distributor tis input into the switching power supply 5 formed of a DC/DC converter 5d, and direct current output voltage (12V DC) to be supplied to the server 4 is generated by the switching power supply 5 (DC/DC converter 5d). This kind of power supply system is called, for example, a high-voltage direct current power supply system (HVDC) (for example, refer to NPL 1).
Also, the power supply system shown in FIG. 14 is such that high-voltage direct current power (400V DC) obtained from the AC/DC converter 1b of the uninterruptible power supply system 1 is converted into low-voltage direct current voltage (48V DC) via a DC/DC converter 1d provided in the uninterruptible power supply system 1, and supplied to the direct current power distributor 2. Further, the load apparatus side is configured so that direct current low voltage supplied from the power distributor 2 is input into the switching power supply 5 formed of a DC/DC converter 5e, and direct current output voltage (12V DC) to be supplied to the server 4 is generated by the switching power supply 5 (DC/DC converter 5e). This kind of power supply system is called, for example, a low-voltage direct current power supply system (for example, refer to NPL 2).
As technology relating to the uninterruptible power supply system 1 in the heretofore described power supply systems, it is disclosed in, for example, PTL 2 that uninterruptible power supply systems are operated in parallel. Also, it is disclosed in PTL 3 that when increasing the number of uninterruptible power supply systems operated in parallel, only the batteries are connected in parallel by switching, because of which the battery capacities are changed.